Cleaning metal surface



Patented Nov. 5, 192 9 un -ran STATES PATENT OFFICE .ADLEB, OF CHICAGO HEIGHTS, ILLINOIS, ASSIGNQB, TO DIVERSE! MANUFAC- TUBING COMPANY, A CORPORATION OF ILLINOIS CLEANING METAL SURFACE 80 Drawing.

scription, in which specific examples illustrating my invention will be more fully set forth.

Tin plated sheet metal and containers there of, particularly when used in the handling 10 of food products such as milk, cream or the like, become covered with fatty deposits, for the removal of which it has hitherto been customary to employ alkaline cleaners, such as sodium carbonate, trisodium phosphate,

soap powders, borax and the like. Such containers, for example, milk and cream cans, require frequent and thorough cleaning and it has been found that the action of cleaning agents such as those hitherto used result in a corrosion and checking of the tin plating.

The life-of the tin plating is thus greatly lessened, and frequently replating is required In accordance with this invention, the

checking and corrosion of the tin plating under the action of the cleaning agent of an alkaline nature are prevented by providing during the cleansing, a chromate compound, the presence of which I have found to inhibit or entirely prevent the checking and corrosion of the plating. It is preferred that the chromate compound be incorporated in or admixed with the alkaline cleaning agent from which the cleaning solution for washing the tin platedmetal or container is made. If

desired, however, the oxidizing agent may be separately incorporated in the alkaline cleaning solution.

The alkaline cleaning agent employed in carrying out this invention may be one of the ordinary alkaline substances used for that purpose; for example, trisodium phosphate, soda ash, soap powder, borax, caustic alkali, or the like. It is preferred, however, that the caustic alkalies such as sodium hydroxide, be

Application filed Mai-ch29, 1926. Serial No. 98,404.

not employed. The chromate compound may be a water soluble chromate or dichromate,

preferably of an alkali metal, as sodium, am-

monium or potassium dichromate or chromate.

The proportion of the chromate compound relative to the alkaline substance may be greatly varied; thus, proportions as low as 1% of the alkaline cleansing agents are found to substantially inhibit-checking or corrosion of the tin plating. Proportions up to l0% may be employed, or even higher if desired, although in general, a suitable range is from 3 to 5% of the oxidizing agent. -In preparing the cleansing solution, from to 8 ounces of the cleaning alkaline substance may be employed per gallon of water, together with the desired proportion of the oxidizing agent. Thus, one-half ounce of trisodium phosphate per gallon of water is found to have an appreciable checking action upon tin plate in ten minutes at a temperature of 65 C. The addition of 1% of potassium dichromate (based upon the amount of trisodium phosphate) substantially inhibits checking action with concentrations as high as eight ounces per gallon when the application is continued up to sixty minutes at 65 C. From 3 to 5% of potassium dichromate completely prevents checking on a treatment of tin plated surfaces with concentrations up to eight ounces per gallon for ten minutes at 65 (1., and substantially inhibits checking action with concentrations of trisodium phosphate up to eight ounces per gallon when treatment is continued for sixty minutes at 75 C.

Soda ash, in concentrations as low as onehalf ounce per gallon, causes checking within sium dichromate appreciably inhibits checking.

Three to five Her cent of potassium dichromate substantia y prevents checking by soda ash even in concentrations up to eight ounces per gallon and at temperatures of 75 0. when treatment is continued as long as sixty minutes.

Other chromates and dichromates, for example, sodium dichromate are similar in their action topotassium dichromate as set forth above. V

My preferred composition is one containing trisodium phosphate and a chromate compound; for example, 3 to; 5% of potassium dichromate or sodium dichromate.

I claim:

1. The method of cleaning tinned metal surfaces and inhibiting corrosion of the tin thereof which comprises subjecting such surfaces to the action of a water soluble chromate compound and of an alkaline detergent.

2. The method of cleaning tinned metal surfaces and inhibiting corrosion of the tin thereof which comprises-subjectin such surfaces to the action of a solution of trisodium phosphate in the presence of a dichromate of an alkali metal.

3. The method of cleaning tinned metal surfaces and inhibiting corrosion of the tin thereof which comprises subjecting such surfaces to the action of a solution of trisodium phosphate in the presence of sodium dichromate.

4. A detergent for tinnedmetal surfaces comprising a major portion of a soluble noncaustic alkaline detergent and a minor portion of a water soluble chromate compound.

5. A detergent for tinned metal surfaces comprising a majorportion of a soluble noncaustic alkaline detergent and a minor portion of a dichromate of an alkali metal.

6. A detergent composition for tinned metal surfaces comprismg a major portion of trisodium phosphate and a minor portion of sodium dichromate.

7. The method of cleaning tinned metal surfaces and inhibiting corrosion of the tin thereof which comprises subjecting such surfaces to the action of a solution of trisodium phosphate in the presence of a dichromate of an alkali metal, the dichromate being present in an amount equal to from one to five percent of the trisodium phosphate.

8. The method of cleaning tinned metal surfaces and inhibiting corrosion of the tin thereof which comprises subjecting such surfaces to the action of a solution of trisodium phosphate in the presence of sodium dichromate,'the sodium dichromate being present in an amount equal to from one to five percent of the trisodium phosphate.

9. A detergent for tinned metal surfaces comprising a soluble non-caustic alkaline demetal surfaces comprising trisodium phos- I phate and sodium dichromate, the sodium dichromate bein present in an amount equal to from one to ve percent of the trisodium phosphate.

11. The method of cleaning tinned metalagainst corrosion and checking.

HOWARD ADLER'.

tergent and a dichromate of an alkali metal,

the alkali' dichromate being resent in an amount equal to from one to ve percent of the alkaline detergent. w i

10. A detergent composition for tinned 

